This invention relates to a fuel delivery control apparatus for controlling an internal combustion engine operable on gasoline fuel or gasoline/alcohol fuel blend particularly in the event of failure of an alcohol concentration sensor or its associated circuit.
For example, Japanese Patent Kokai No. 56-98540 discloses an apparatus for controlling an internal combustion engine operable on gasoline fuel or gasoline/alcohol fuel blend. The engine control apparatus employs an alcohol concentration sensor sensitive to the alcohol concentration of the fuel delivered to the engine. The sensed alcohol concentration is used to control the amount of fuel metered to the engine.
With such a conventional engine control apparatus, however, the engine cannot operate in a stable manner in the event of failure of the alcohol concentration sensor or its associated circuit.